JP2007180200A - Method and device for reading discrimination mark - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method and a device for reading a discrimination mark capable of reading a discrimination mark even if a main surface side of a wafer where the discrimination mark is formed is sealed with resin. <P>SOLUTION: A reading device A for a discrimination mark 20 comprises an illumination unit 13 equipped with a light source 10 for emitting infrared beam, and an imaging unit 16 which receives the reflection light of infrared beam for imaging emitted from the illumination unit 13 toward a wafer 1. The infrared beam is so emitted as the optical axis crosses a main surface 1c of the wafer 1 from a rear surface 1b side of the wafer 1. The reflection light of the infrared beam is received and imaged, that has transmitted the wafer 1 and is reflected on the main surface 1c side to read the discrimination mark 20 formed on the main surface 1c side of the wafer 1. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a method for reading an identification mark such as a wafer number or a lot number formed on a wafer, and an identification mark reading apparatus.

  Conventionally, at a site where a semiconductor device is manufactured, a plurality of wafers (for example, one lot of wafers) housed in a single storage case move between processes for manufacturing a semiconductor device. In general, since there are many processes to be performed for each wafer, identification marks such as product type, model number, lot number, and wafer number are displayed on each wafer to prevent wafer confusion due to process complications. Prevention of this is made.

  This type of identification mark is formed on the wafer by using, for example, a laser marker, and displays characters and numbers by an aggregate of dot-shaped engravings. Further, when the identification mark is formed on the back surface of the wafer, for example, when the back surface of the wafer is vacuum-sucked and held for the purpose of transporting or supporting the wafer, the main surface of the wafer located on the opposite side of the identification mark is raised. For example, defocusing in a photolithography process or polishing abnormality in a CMP (Chemical Mechanical Polishing) process may occur. For this reason, the identification mark is usually provided on the main surface of the wafer.

Further, the identification mark is recognized using a wafer identification mark reader equipped with a CCD camera, for example, when it is necessary to specify the wafer or lot in the manufacturing process. Furthermore, this type of identification mark reading apparatus includes a transfer robot for taking wafers in and out of the storage case. For example, a plurality of wafers that have been identified by reading the identification mark are identified in ascending or descending order. It can be rearranged in the storage case so as to be (see, for example, Patent Document 1).
JP-A-5-147723

  However, in the above-described reading device for the identification mark formed on the wafer, when the manufacturing process proceeds and the main surface of the wafer is sealed with resin and a resin layer is formed, the identification mark formed on the main surface is resin. There is a problem that the identification mark cannot be recognized. That is, in the manufacture of a semiconductor device, a wafer having a plurality of ICs (integrated circuits) formed on the main surface side is prepared, rewiring electrically connected to the IC is formed through pad electrodes, and further rewiring At the stage where a columnar electrode terminal (metal post) made of, for example, copper is formed thereon, the main surface side is sealed with resin. For this reason, before the IC, rewiring, and metal post are sealed with resin, the identification mark formed on the main surface of the wafer is exposed and can be read visually. There is a problem that the identification mark is hidden by the resin and the wafer or lot cannot be specified.

  In view of the above circumstances, the present invention provides an identification mark reading method and an identification mark reading device that can read the identification mark even when the main surface side of the wafer on which the identification mark is formed is sealed with resin. With the goal.

  In order to achieve the above object, the present invention provides the following means.

  A method for reading an identification mark formed on a wafer according to the present invention is a method for reading an identification mark formed on a wafer, from the back side of the wafer on which a resin layer for sealing the main surface side is formed. By irradiating infrared rays with the axis intersecting the main surface of the wafer, and imaging while receiving the reflected light of the infrared rays transmitted through the wafer and reflected on the main surface side, The identification mark formed on the main surface side is read.

  In the identification mark reading method of the present invention, it is desirable that the infrared ray is irradiated while the optical axis is obliquely intersected with the main surface of the wafer.

  An identification mark reader of the present invention is an apparatus for reading an identification mark formed on a wafer including a resin layer that seals the main surface side, and an illumination unit including a light source that emits infrared rays; And an imaging unit that receives reflected light of the infrared ray emitted from the illumination unit toward the wafer and images the reflected light.

  In the identification mark reader of the present invention, it is preferable that the illumination unit is provided with a fiber bundle that defines an optical path of the infrared ray emitted from the light source.

  Furthermore, in the identification mark reader of the present invention, it is preferable that a reflection mirror for defining an optical path of the infrared ray emitted from the light source is provided.

  According to the identification mark reading method of the present invention, by irradiating infrared rays from the back side of the wafer, the infrared rays can be transmitted through the wafer, and an IC formed on the main surface side of the wafer can be used. Infrared rays can be reflected at the bonding interface with the main surface of the resin layer sealing the rewiring, electrode terminals, and the like. As a result, it is possible to read the identification mark formed on the main surface of the wafer, which could not be read at the stage of being covered with the resin layer, by imaging while receiving the reflected light of the infrared ray. Become.

  In the identification mark reading method of the present invention, the main surface of the wafer is formed in a concave shape by, for example, a laser marker by irradiating infrared rays while obliquely intersecting the main surface of the wafer. A clear image of the identification mark can be acquired. In other words, the main surface at the position excluding the identification mark is substantially flat because the irradiated infrared ray is substantially specularly reflected, whereas the identification mark that is an aggregate of concave dots is irradiated with the infrared ray. Will be irregularly reflected according to the shape of the dent. For this reason, for example, when the infrared ray is irradiated from the direction orthogonal to the main surface, the reflected light is reflected in the direction orthogonal to the main surface, and the image picked up by receiving this is together with the identification mark, For example, an IC pattern formed on the main surface is projected. On the other hand, when the infrared ray is irradiated obliquely with respect to the main surface, the reflected light specularly reflected at the position excluding the identification mark cannot be captured, and only the irregular reflection light according to the concave shape of the identification mark can be captured. By receiving this irregularly reflected light and picking up an image, it is possible to obtain an image in which only the identification mark is projected.

  According to the identification mark reading device of the present invention, the illumination unit that emits infrared rays and the imaging unit that receives the reflected light of the infrared rays reflected from the wafer and images it are provided. The unit can irradiate infrared rays from the back side of the wafer and transmit the wafer, and the reflected light reflected by the main surface of the wafer can be imaged by the imaging unit. As a result, the identification mark formed on the main surface of the wafer can be read.

  In the identification mark reader of the present invention, since the illumination unit is provided with the fiber bundle, the light source can be installed at an arbitrary position, and the infrared ray emitted from the light source can be arbitrarily set. It is possible to irradiate the optical axis in the direction of. This makes it possible to selectively display only the identification mark on the acquired image, or to project, for example, an IC, a pad electrode, or a rewiring formed on the main surface in addition to the identification mark.

  Furthermore, in the identification mark reading device of the present invention, the reflection mirror that defines the optical path of the infrared ray is provided, and the optical angle of the infrared ray emitted from the light source is adjusted by adjusting the installation angle. Can be directed in an arbitrary direction, so that the light source can be installed at an arbitrary position, and only the identification mark is displayed on the acquired image, for example, an IC formed on the main surface in addition to the identification mark. It is possible to selectively display the pattern of the above.

  A method for reading an identification mark formed on a wafer according to a first embodiment of the present invention and a reading apparatus used therefor will be described below with reference to FIGS. The present embodiment relates to a method and a reading apparatus for reading an identification mark of a wafer having a resin layer formed on the main surface side.

  As shown in FIGS. 1 to 2, the identification mark reading device A (hereinafter referred to as the reading device A) of the present embodiment includes a stage unit 2 on which a wafer 1 is placed on an upper surface 2 a and an upper part of the stage unit 2. A first imaging unit 3 that captures an external appearance image of the wafer 1, a second imaging unit 4 that is disposed below the stage unit 2 and reads an identification mark of the wafer 1, and a plurality of wafers 1 are accommodated therein. A first storage case mounting table 6 on which the first storage case 5 is mounted; a second storage case mounting table 8 on which a second storage case 7 capable of storing a plurality of wafers 1 is mounted; The transfer unit 9 is configured to transfer the wafer 1 between the first storage case 5 or the second storage case 7 and the stage unit 2. Here, the stage unit 2 is disposed to face the first storage case mounting table 6 and the second storage case mounting table 8 with the transport unit 9 therebetween.

  The stage portion 2 is formed in a substantially rectangular disk shape, and an opening 2c having a circular cross section penetrating from the upper surface to the lower surface is formed in a substantially central portion. In this opening 2c, for example, a suction part 2f composed of a cylindrical suction body part 2d and a suction pad 2e for sucking and holding the wafer 1 at the tip of the suction body part 2d can be retracted and rotated around the axis O1. Is inserted. The suction portion 2f has an inner hole of the suction body portion 2d connected to a vacuum suction means such as a vacuum pump, and drives the vacuum suction means by bringing the suction pad 2e into contact with the back surface 1b of the wafer 1. The suction pad 2e is supposed to behave as a suction cup. Further, the stage portion 2 is formed with a concave portion 2h that is recessed in a direction orthogonal to the other side surface 2g on the other side surface 2g side that is opposite to the one side surface 2b that faces the transport unit 9. The concave portion 2h is provided such that a part of the outer peripheral edge side of the wafer 1 placed on the upper surface 2a of the stage portion 2 overlaps the concave portion 2h.

  As shown in FIG. 2, the first imaging unit 3 includes an imaging unit 3a such as a CCD camera and a wafer position recognition device 3b connected to the imaging unit 3a. The imaging unit 3 a is installed so that its optical axis is orthogonal to the upper surface 2 a of the stage unit 2. Further, the wafer position recognition device 3b detects the position of the outer periphery of the wafer 1 or the position of the notch 1a shown in FIG. It is possible to specify the position of. Further, a display unit 3c such as a monitor is connected to the wafer position recognition device 3b, and an image of the wafer 1 acquired by the imaging unit 3a can be displayed by the display unit 3c.

  As shown in FIGS. 2 to 3, the second imaging unit 4 includes an IR (Infra-red) light source (light source) 10 that can emit infrared light having a wavelength of 1100 nm or more and an infrared light emitted from the IR light source 10. An illumination unit 13 including a fiber bundle 11 that defines an optical path of the light beam and a reflection mirror 12 that changes the direction of infrared light emitted from the tip (other end) of the fiber bundle 11, a lens 14, and an image sensor 15 are provided. IR camera (imaging unit) 16.

  The IR light source 10 of the illumination unit 13 is housed in a rectangular box-shaped housing. One end of the fiber bundle 11 is arranged inside the housing, and the other end extends to the vicinity of the reflection mirror 12 provided in the IR camera 16. The fiber bundle 11 receives infrared rays emitted from the IR light source 10 at one end, and can emit infrared rays received at one end toward the reflection mirror 12 from the other end. The reflection mirror 12 is provided inside a casing 16a of an IR camera 16 to be described later, and can change the direction of infrared light emitted from the other end of the fiber bundle 11 to irradiate the wafer 1 positioned above with infrared light. It is installed at an angle. In addition, the reflection mirror 12 is a half mirror.

  In the IR camera 16, for example, a lens 14 and an image sensor 15 disposed below the lens 14 are provided inside a casing 16 a formed in a cylindrical shape. In addition, the wiring connected to the image sensor 15 extends outward from the lower end side of the housing 16a and is connected to a display unit 16b such as a monitor. Here, the reflection mirror 12 described above is provided so that the optical axis of the optical system of the IR camera 16 and the optical axis of the infrared ray whose direction is changed by the reflection mirror 12 are arranged on the same straight line. And located above the lens 14.

  As shown in FIGS. 1 to 2, the first storage case mounting table 6 and the second storage case mounting table 8 include a first storage case 5 storing a plurality of wafers 1 as an upper surface of the first storage case mounting table 6. A second storage case 7 capable of storing a plurality of wafers 1 is placed on the upper surface 8 a of the second storage case mounting table 8. Here, the first storage case 5 and the second storage case 7 are each formed in a substantially rectangular box shape, and the transport unit is installed on the first storage case mounting table 6 and the second storage case mounting table 8. Each side surface 5a, 7a facing the 9 side is opened. In addition, the first storage case 5 and the second storage case 7 are provided with a plurality of slots arranged in the interior thereof, and one wafer 1 is inserted into each slot, and a plurality of wafers 1 are regularly arranged. It is supposed that they are arranged as one lot. Furthermore, the first storage case 5 and the second storage case 7 can be moved up and down by providing drive means on the first storage case mounting table 6 and the second storage case mounting table 8, for example. Further, for example, a control means (not shown) is connected to the driving means, and each of the first storage case 5 and the second storage case 7 can be moved up and down appropriately by one slot.

  As shown in FIGS. 1 and 2, the transport unit is connected to an XY table 9c, a rotary actuator 9d mounted vertically upward on the XY table 9c, and an upper end of a rotary shaft 9e of the rotary actuator 9d. An articulated arm 17 is used. The multi-joint arm 17 includes a first arm 17a, a second arm 17b, and a third arm 17c that are arranged in parallel in the horizontal direction, and the first arm 17a rotates with one end connected to the upper end of the rotary shaft 9e. It is assumed that it follows the rotation of the shaft 9e. The second arm 17b is rotatably supported at one end on the other end of the first arm 17a, and is rotatable about the other end of the first arm 17a by a built-in belt transmission device 17d. One end of the third arm 17c is rotatably supported on the other end of the second arm 17b, and is rotatable about the other end of the second arm 17b by a built-in belt transmission device 17e. Further, the third arm 17c is formed in a bifurcated shape on the other end side, and a convex support portion 18 is provided on each upper surface of the branched other end side. A vacuum suction port (not shown) is formed in the support portion 18, and the vacuum suction port communicates with a suction path (not shown) provided inside the third arm 17 c. Further, a vacuum suction means such as a vacuum pump is connected to the suction path.

  Next, the wafer 1 according to the present embodiment is formed, for example, by forming polycrystalline or single crystal silicon into a disk shape. As shown in FIGS. 4 to 5, an IC (integrated circuit) 1d is formed on the main surface 1c. A rewiring 1f electrically connected to the IC 1d through the pad electrode 1e, and a columnar electrode terminal (metal post) 1g made of, for example, copper formed on the rewiring 1f are provided. Further, a resin layer (sealing resin) 1h is formed on the main surface 1c, and the IC 1d, the rewiring 1f, and the metal post 1g are sealed with the resin layer 1h. The resin layer 1h is formed such that the other surface 1i is parallel to one surface bonded to the main surface 1c of the wafer 1, and the upper surface of the metal post 1g is located on the same plane as the other surface 1i and is exposed. is doing.

  On the other hand, an identification mark 20 such as a lot number or a wafer number as shown in FIGS. 6 to 7, for example, is formed on a part of the outer peripheral side of the main surface 1c. The identification mark 20 is formed in a concave shape using, for example, a laser marker, and displays characters and numbers by an aggregate of dot-shaped engravings. One dot diameter of the identification mark 20 is, for example, about 20 to 500 μm. In addition, the outer peripheral edge located opposite to the identification mark 20 is notched in a V shape in the wafer 1, and the notched portion serves as a notch 1 a that serves as a mark for specifying the position of the wafer 1. . Incidentally, the lattice-like portion of the main surface 1 c of the wafer 1 shown in FIG. 4 shows a dicing line 23 when the wafer 1 is diced and the semiconductor device 22 is separated into pieces, and is surrounded by the dicing line 23. The rectangular portion is one semiconductor device 22.

  Here, as shown in FIG. 5, the identification mark 20 formed on the main surface 1c of the wafer 1 is completely covered with the resin layer 1h when the main surface 1c is sealed with the resin layer 1h. It becomes covered and cannot be read with a CCD camera or the like that shoots visually or irradiates visible light, for example, and picks up an image while receiving the reflected light. For this reason, the problem that it became impossible to identify the wafer 1 after resin sealing has arisen.

  Next, a method for reading the identification mark 20 formed on the wafer 1 using the identification mark 20 reading device A having the above-described configuration will be described.

  First, a first storage case 5 storing a plurality of wafers 1 is mounted on the first storage case mounting table 6, and an empty second storage case 7 is mounted on the second storage case mounting table 8. . Next, the transfer unit 9 is driven to insert the bifurcated tip portion of the third arm 17 c into the first storage case 5, and the support unit 18 is brought into contact with the back surface 1 b of one wafer 1 to be transferred. The wafer 1 is sucked and held on the support unit 18.

  Then, the attracted and held wafer 1 is taken out from the first storage case 5 and transferred onto the stage unit 2. Next, the suction part 2f is projected from the opening 2c of the stage part 2, and the suction pad 2e is brought into contact with the approximate center position of the wafer 1 held by the third arm 17c, and the vacuum suction means connected to the suction body part 2d is driven. Then, the wafer 1 is sucked and held. At this stage, the suction of the support portion 18 of the third arm 17c is released, and the transport portion 9 is returned to the original position. Thus, the transfer of the wafer 1 from the first storage case 5 to the stage unit 2 is completed.

  On the other hand, at this stage, the wafer 1 held by the suction unit 2f is in an unknown state where the identification mark 20 is located. For this reason, the first image pickup unit 3 picks up an appearance image of the wafer 1 and specifies the position of the wafer 1 by the wafer position recognition device 3b depending on the outer periphery of the wafer 1 and the position of the notch 1a. At the stage where the current position of the wafer 1 is specified, the suction portion 2f is rotated around the axis O1, and the wafer 1 is moved so that the notch 1a is arranged at a predetermined position. Then, the suction part 2 f is returned to the opening 2 c of the stage part 2 while releasing the suction of the suction pad 2 e, and the wafer 1 is placed on the upper surface 2 a of the stage part 2. The wafer 1 placed in this way is placed so that the formation position of the identification mark 20 overlaps the concave portion 2 h of the stage portion 2.

  Next, an infrared ray is emitted from the IR light source 10 of the second imaging unit 4. This infrared ray is emitted from the other end through the fiber bundle 11 and applied to the reflection mirror 12. Then, the direction is changed so that the optical axis of the infrared ray is orthogonal to the main surface 1 c of the wafer 1 by the reflection mirror 12, and the rear surface 1 b of the wafer 1 is irradiated through the concave portion 2 h of the stage portion 2.

  The infrared ray irradiated to the back surface 1b of the wafer 1 passes through the wafer 1 because the wavelength of the infrared ray is 1100 nm or more. In the wavelength region, the transmitted infrared ray is absorbed in the resin layer 1h or transmitted through the resin layer 1h, and a large amount is reflected at the bonding interface between the resin layer 1h and the main surface 1c of the wafer 1. The reflected infrared ray (reflected light) passes through the wafer 1 again and is emitted to the outside of the wafer 1, passes through the reflecting mirror 12 that is a half mirror, and is received by the lens 14 of the IR camera 16 and collected. The light is imaged by the image sensor 15. As a result, an image of the identification mark 20 formed on the main surface 1c of the wafer 1 is acquired and displayed on the display unit 16b connected to the imaging element 15 via the wiring. By confirming this display image, the identification mark 20 of the wafer 1 after the resin layer 1h is formed can be read.

  Here, in the present embodiment, the infrared ray is irradiated onto the wafer 1 by the reflecting mirror 12 with its optical axis being orthogonal to the main surface 1c of the wafer 1, so as shown in FIG. The reflected light reflected by the substantially planar main surface 1c excluding the concave identification mark 20 has its optical axis directed in a direction orthogonal to the main surface 1c. For this reason, an image picked up by the IR camera 16 installed with the optical axis of the optical system oriented in a direction orthogonal to the main surface 1c is formed in the vicinity of the identification mark 20 on the main surface 1c, for example, as shown in FIG. For example, the IC1d pattern and the like are also copied at the same time.

  At the stage where the image acquisition in which the identification mark 20 is projected is completed, the wafer 1 is brought into contact with the suction pad 2e of the suction portion 2f and sucked and held again, and is transferred to the transport portion 9. And it is accommodated in the slot of the 2nd storage case 7 mounted in the 2nd storage case mounting base 8 by the conveyance part 9. FIG. At this time, the wafer 1 is stored in a predetermined slot corresponding to the read identification mark 20. By repeatedly performing the same operation as described above on the plurality of wafers 1 in the first storage case 5, the plurality of wafers 1 are aligned such that the numbers of the identification marks 20 are in ascending order or descending order, for example. 7 is stored.

  Therefore, in the method for reading the identification mark 20 formed on the wafer 1 and the reading device A, the illumination unit 13 capable of emitting infrared rays is provided, so that the wafer 1 is irradiated with infrared rays. Thus, the irradiated infrared ray can be transmitted through the wafer 1 and reflected at the bonding interface between the resin layer 1 h and the main surface 1 c of the wafer 1. Further, since the IR camera (imaging unit) 16 capable of imaging while receiving reflected light of infrared rays is provided, the reflected infrared rays can be received and imaged. Thereby, it is possible to acquire an image of the main surface 1c of the wafer 1 by irradiating infrared rays from the back surface 1b side of the wafer 1, and to read the identification mark 20 formed on the main surface 1c. . Therefore, it is possible to read the identification mark 20 on the wafer 1 that has been sealed with resin, and specify the wafer 1 or lot.

  Further, by providing the reflection mirror 12, the direction of the optical axis of the infrared ray irradiated toward the wafer 1 can be set to an arbitrary direction. Thereby, the installation position of IC light source 10 can be made arbitrary.

  In addition, this invention is not limited to said 1st Embodiment, In the range which does not deviate from the meaning, it can change suitably. For example, in the present embodiment, the reading device A for the identification mark 20 includes the stage unit 2, the first imaging unit 3, the second imaging unit 4, the first storage case mounting table 6, the second storage case mounting table 8, and the transport unit. However, it is sufficient that at least the second imaging unit 4 is provided. In addition, the second imaging unit 4 includes the illumination unit 13 including the IR light source 10, the fiber bundle 11, and the reflection mirror 12, and the imaging unit 16 including the lens 14 and the imaging element 15. The illumination unit 13 only needs to include the IR light source 10 that emits infrared rays. In this case, for example, a lens that receives infrared rays emitted from the IR light source 10 and collects the infrared rays may be provided, and the wafer 1 may be irradiated with infrared rays via this lens. .

  In relation to this, the second imaging unit 4 is provided in another device such as an appearance inspection device provided in the manufacturing process of the semiconductor device, and an existing stage unit or transfer unit such as an appearance inspection device, or a storage case mounting table. The identification mark 20 of the wafer 1 may be read when an appearance inspection or the like is performed while using. In addition, the first imaging unit 3 of the present embodiment is for specifying the position of the wafer 1. However, for example, the acquired image is used for appearance inspection or the wafer 1 is identified before the resin layer 1 h is formed. It may be used to read the mark 20.

  In addition, the illumination unit 13 includes the IR light source 10 in a rectangular box-shaped housing, and the imaging unit 16 includes the lens 14 and the image sensor 15 in a cylindrical housing 16a. The shape need not be limited. In the present embodiment, the reflection mirror 12 of the illumination unit 13 is provided inside the housing 16a of the imaging unit 16. However, when the reflection mirror 12 is used, for example, as shown in FIG. The reflection mirror 12 may be integrally formed on the other end side of the fiber bundle 11 of the illumination unit 13 via the box 12a, and the reflection mirror 12 and the imaging unit 16 may be provided separately. In this case, the reflection mirror 12 is disposed between the imaging unit 16 and the wafer 1 while holding the optical axis of the infrared ray polarized by the reflection mirror 12 so as to intersect the main surface 1 c of the wafer 1. Thus, the identification mark 20 can be read. Further, the reflection mirror 12 may not be a half mirror when not installed on the optical axis of the optical system of the imaging unit 16.

  Furthermore, in the present embodiment, the imaging unit 16 is provided so that its optical axis is orthogonal to the back surface 1 b of the wafer 1, but the imaging unit 16 has an optical axis on the main surface 1 c of the wafer 1. What is necessary is just to be provided so that it may cross.

  In the present embodiment, the wavelength of the infrared light emitted from the IR light source 10 has been described as being 1100 nm or more. However, if the light is in the infrared region, the wavelength needs to be limited to 1100 nm or more. There is no. Furthermore, although the wafer 1 is made of polycrystalline or single crystal silicon, the wafer 1 is not necessarily limited to silicon. In addition, as shown in FIG. 9, for example, the present invention is applied to the wafer 1 in which a dicing tape 24 is attached to the back surface 1 b of the wafer 1 or the wafer 1 after dicing is held by the dicing tape 24. On the other hand, it is also possible to read the identification mark 20 formed on the main surface 1c by transmitting the infrared light emitted from the illumination unit 13 through the dicing tape 24.

  Furthermore, although the diameter of each dot of the identification mark 20 formed on the wafer 1 is about 20 to 500 μm, the present invention reads the identification mark 20 formed with a diameter smaller than this dot diameter. Is also possible.

  Next, an identification mark reading method and a reading apparatus used therefor according to a second embodiment of the present invention will be described with reference to FIG. In the description of the present embodiment, the same reference numerals are assigned to configurations common to the first embodiment, and the detailed description thereof is omitted.

  The reading device B for the identification mark 20 of the present embodiment is different from the first embodiment only in the configuration of the second imaging unit 4, and the other configurations are the same. As shown in FIG. 10, the second imaging unit 4 includes an IR (Infra-red) light source (light source) 10 that can emit infrared light having a wavelength of 1100 nm or more, and the infrared light emitted from the IR light source 10. The illumination unit 13 includes a fiber bundle 11 that defines an optical path, and an IR camera (imaging unit) 16 that includes a lens 14 and an image sensor 15.

  The illumination unit 13 has an IR light source 10 disposed inside a rectangular box-shaped housing, one end of the fiber bundle 11 is disposed inside the housing, and can receive infrared rays emitted from the IR light source 10. The infrared light received from one end is extended from the other end and can be emitted from the other end. The fiber bundle 11 is a flexible structure that can freely change the direction and position of the other end.

  Next, a method for reading the identification mark 20 using the reading device B for the identification mark 20 formed on the wafer 1 having the above-described configuration will be described.

  As in the first embodiment, when the wafer 1 is placed on the stage unit 2, infrared light is emitted from the IR light source 10, and the infrared light is directed from the other end of the fiber bundle 11 toward the back surface 1 b of the wafer 1. And exit. At this time, the fiber bundle 11 is freely displaced and installed so that the optical axis of the infrared ray emitted from the other end obliquely intersects the main surface 1 c of the wafer 1.

  As in the first embodiment, since the wavelength of the infrared ray applied to the back surface 1b of the wafer 1 is 1100 nm or more, the infrared light passes through the wafer 1 and passes between the resin layer 1h and the main surface 1c of the wafer 1. Reflected at the bonding interface. The reflected infrared ray (reflected light) passes through the wafer 1 again and is collected while being received by the lens 14 of the IR camera 16, and is imaged by the image sensor 15. Thereby, an image showing the identification mark 20 is displayed on the display unit 16b, and the wafer 1 can be specified.

  Here, in this embodiment, the infrared ray is irradiated onto the wafer 1 by the fiber bundle 11 of the flexible structure so that the optical axis thereof is obliquely intersecting the main surface 1c of the wafer 1. As shown in FIG. 11, regular reflection is performed on the substantially planar main surface 1 c excluding the concave identification mark 20. On the other hand, in the identification mark 20 which is an aggregate of concave dots, the irradiated infrared ray is irregularly reflected according to the concave shape. In this embodiment, since the IR camera 16 is installed with the optical axis of the optical system oriented in a direction orthogonal to the main surface 1c, the IR camera 16 reflects the reflected light regularly reflected by the main surface 1c excluding the identification mark 20. Of the reflected light irregularly reflected by the identification mark 20, only the reflected light reflected in the optical axis direction of the optical system of the IR camera 16 is received and an image is captured. Thus, unlike the first embodiment, for example, as shown in FIG. 12, the captured image does not include, for example, the IC1d pattern formed near the identification mark 20 on the main surface 1c, and only the identification mark 20 is present. Will be projected clearly.

  Therefore, in the above-described method for reading the identification mark 20 and the reading device B, the infrared ray emitted from the fiber bundle 11 of the illumination unit 13 is directly applied to the wafer 1 and the reflected light is imaged by the IR camera 16. The identification mark 20 on the wafer 1 can be read. As a result, the identification mark 20 that cannot be recognized visually or by a CCD camera or the like with the formation of the resin layer 1h can be read, and the wafer 1 or lot can be specified.

  Further, since infrared rays can be irradiated in a direction that obliquely intersects the optical axis with respect to the main surface 1 c of the wafer 1, the optical axis of the optical system of the IR camera 16 is abbreviated except for the identification mark 20. By installing the IR camera 16 so that it does not coincide with the optical axis of the reflected light that is regularly reflected on the planar main surface 1c, it is possible to receive only the reflected light that is irregularly reflected by the identification mark 20 and acquire an image. Become. Thereby, for example, an IC1d pattern or the like is not projected, and an image in which only the identification mark 20 is clearly projected can be acquired.

  In addition, this invention is not limited to said 2nd Embodiment, In the range which does not deviate from the meaning, it can change suitably. For example, in this embodiment, the optical axis of the infrared ray emitted from the other end of the fiber bundle 11 of the illumination unit 13 is assumed to obliquely intersect the main surface 1c of the wafer 1. However, the present invention is not limited to this. Similarly to the embodiment, the irradiation may be performed so as to be orthogonal to the main surface 1c of the wafer 1. Further, although the description has been made assuming that the imaging unit 16 is provided so that the optical axis of the optical system of the imaging unit 16 is orthogonal to the main surface 1c of the wafer 1, the optical axis of the imaging unit 16 is also the wafer 1. The main surface 1c may be provided so as to cross obliquely. In this case, the identification mark 20 shown in the present embodiment is clearly displayed by shifting the optical axis of the reflected light regularly reflected by the main surface 1c excluding the identification mark 20 and the optical axis of the imaging unit 16. Acquired images can be obtained.

It is a figure which shows the reading device of the identification mark formed in the wafer which concerns on 1st Embodiment of this invention. It is a side view of FIG. It is a figure which shows the illumination unit of FIG. It is the figure shown as an example of the wafer which concerns on 1st Embodiment of this invention. It is sectional drawing of the wafer of FIG. It is a figure which shows the relationship between the infrared ray irradiated toward the wafer from the reading apparatus of the identification mark which concerns on 1st Embodiment of this invention, and its reflected light. It is the figure which showed an example of the image acquired with the reading apparatus of the identification mark which concerns on 1st Embodiment of this invention. It is a figure which shows the modification of the reading apparatus of the identification mark formed in the wafer which concerns on 1st Embodiment of this invention. It is a figure which shows the modification of the reading apparatus of the identification mark formed in the wafer which concerns on 1st Embodiment of this invention. It is a figure which shows the reading apparatus of the identification mark formed in the wafer which concerns on 2nd Embodiment of this invention. It is a figure which shows the relationship between the infrared ray irradiated toward the wafer from the reading apparatus of the identification mark which concerns on 2nd Embodiment of this invention, and its reflected light. It is the figure which showed an example of the image acquired with the reader of the identification mark formed in the wafer which concerns on 2nd Embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Wafer, 1a ... Notch, 1b ... Back surface, 1c ... Main surface, 1h ... Resin layer (sealing resin), 2 ... Stage part, 3 ... 1st Imaging unit, 4... Second imaging unit, 5... First storage case, 6... First storage case mounting table, 7. Table, 9 ... Conveying unit, 10 ... IR light source (light source), 11 ... Fiber bundle, 12 ... Reflection mirror, 13 ... Illumination unit, 14 ... Lens, 15 ... Image sensor, 16 ... IR camera (imaging unit), 20 ... identification mark, 24 ... dicing tape, A, B ... identification mark reader

Claims (5)

A method for reading an identification mark formed on a wafer,
From the back surface side of the wafer on which the resin layer for sealing the main surface side is formed, irradiate infrared rays while crossing the optical axis with the main surface of the wafer, and transmit the wafer through the main surface side. An identification mark reading method, wherein the identification mark formed on the main surface side of the wafer is read by imaging while receiving reflected light of the reflected infrared ray. In the reading method of the identification mark according to claim 1,
A method of reading an identification mark, wherein the infrared ray is irradiated while the optical axis is obliquely intersected with a main surface of the wafer. An apparatus for reading an identification mark formed on a wafer having a resin layer for sealing the main surface side,
An illumination unit including a light source that emits infrared rays, and an imaging unit that receives reflected light of the infrared rays emitted from the illumination unit toward the wafer and images the reflected light. Identification mark reader. In the reading device of the identification mark according to claim 3,
An identification mark reading apparatus, wherein the illumination unit is provided with a fiber bundle that defines an optical path of the infrared ray emitted from the light source. In the reading apparatus of the identification mark of Claim 3 or Claim 4,
An identification mark reading apparatus, wherein a reflection mirror for defining an optical path of the infrared ray emitted from the light source is provided.

Images